Method of assembling a distalizer

ABSTRACT

Method of assembling a distalizer comprising a mesial element and a distal element, and an arm connecting the distal element with the mesial element, the arm comprising a ball member at one end of the arm and the distal element comprising a receptacle for receiving said ball member, the method comprising providing the distal element with an opening of the receptacle that is large enough to introduce the ball member substantially without deformation, providing the arm with the ball member, introducing the ball member into the receptacle, and reducing the opening of the receptacle. The disclosure further relates to a distalizer obtainable by such a method.

The present invention relates to a method of assembling a distalizer,and more particularly relates to a method of assembling a distalizerthat comprises at least two elements: a mesial element destined to befixed to the surface of an upper canine, and a distal element destinedto be attached to the surface of an upper molar, in particular the upperfirst molar.

BACKGROUND ART

Depending on a patient's malocclusion, a variety of orthodontictreatments is available. In some of these treatments, extraction ofteeth may be required in order to create space for the remaining teeth.In some treatments, a distalizing element may be used, possibly incombination with the extraction of one or more teeth.

A particular distalizing element is known from e.g. EP 1 433 435 and EP1 649 824. These distalizers are especially adapted for the segmentaldistalization of the canine-to-molar posterior maxillary area. Thedistalizers of these documents comprise a mesial element which may befixed by its base to an upper canine, and further comprises a distalelement which may be fixed by its base to an upper molar, in particularthe first molar.

The mesial element in these designs comprises both a base, and an armthat connects it to the distal element. The arm may be substantiallyarch shaped and may comprise a ball member at one of its ends. This ballmember is received in a receptacle of the distal element that has acomplementary shape to the ball member.

The mesial element may comprise a blunt projection that extendssubstantially forwards which may serve as a hooking element. In use, abracket with a hook may be attached to a mandibular molar and an(orthodontic) rubber band may be suspended around this hook and thehooking element on the mesial element.

This way, a force pulling the maxillary canine backwards is provided. Ifthe patient is wearing e.g. a splint (or another fixation device) thatacts as a solid anchor and fixes the teeth of the mandibule in position,it may be ensured that the teeth in the mandibule do not move forwards,and that the maxillary canine is pulled backwards.

Due to the connection between the mesial element and the distal elementof the distalizer, the maxillary molar may thus also be pushedbackwards. At the same time, due to the shape of the arm in between thecanine and the molar and due to the position of the distal element onthe molar, a rotational force is also exerted upon the molar. Thisrotational force may result in a pivot about the palatal root of themaxillary molar. Also, a rotation in the distal direction of the molar(“uprighting”) may result. Thus a backwards force and a rotational forcemay be exerted upon the molar at the same time.

In order to avoid that the maxillary molar rotates too much in thedistal direction (i.e. in this case, it would assume an orientation inwhich it is tilted backwards), the shape of the receptacle and the ballmember are such that with a predetermined rotation of the ball memberwith respect to the upper molar, the ball member touches the inside ofthe receptacle and cannot rotate further. To this end, both the mesialelement and distal element are mounted at the right height on the molarand canine and are mounted substantially straight along the locallydefined mandibule-maxilla (straight up-down) direction on the surface ofthe tooth. The arm is provided at a predefined angle with respect to theball element. When both the canine and molar are actually straight, thisangle will make sure that the ball member touches the border of thereceptacle and cannot rotate further.

Similarly, the shape of the ball member and the border of the receptaclemay be such that a rotation of the upper molar around its palatal rootmay be limited. Once a predetermined rotation is reached, the ballmember may touch the border of the receptacle and not be able to rotatefurther.

It may thus be ensured that a distalization of the canine-molar segmentmay be combined with a proper (re)orientation of the set of teeth in themaxillary posterior region.

It is thus important that the ball member fits well in the receptacle ofthe distal segment. It is furthermore important that the ball memberonce inserted in the receptacle, stays in the receptacle and cannot slipout.

In the prior art, the method of assembling the distalizer comprisesproviding both the distal element and the mesial element of thedistalizer, the arm connecting both elements being integrally formedwith the mesial element. A receptacle is foreseen in the distal elementand the receptacle comprises an opening for the introduction of the ballmember at the end of the arm.

The ball element is slightly larger than the opening of the receptacle.The ball element is pushed into the receptacle. Upon introduction, theball element and the border of the receptacle experience somedeformation so that the ball is able to enter into the receptacle. Thisdeformation may be mostly elastic, but the ball element could beslightly damaged. Given the importance of the ball element in thefunctioning of the distalizer, it is very important that the dimensionsof the ball element and receptacle are well defined. The forcedintroduction of the ball element in the receptacle may thus cause aproblem.

Additionally, it is possible for the ball element to slip out of thereceptacle.

U.S. Pat. No. 5,620,321 discloses a telescoping mandibular device. Theappliance comprises a pair of telescoping devices that attach on one endto the maxillary arch via a modified ball and socket device and on theother end to the mandibular arch via a modified ball and socket device.During assembly of the appliance in the mouth of the patient, afterintroduction of a ball in the mandibular socket, pliers may be used toplastically deform the mandibular socket legs.

U.S. Pat. No. 5,120,218 discloses an orthodontic traction devicecomprising a connection member and two attachment members. An attachmentmember may be produced with a slot that is transversely enlarged to beof approximately oval shape with its width at the minor axis just enoughto permit the head of the pin to pass through it. Thereafter, with thepin in place the orthodontist applies the beak surface of a pair of jawsto the opposite sides of the device and squeezes to crimp the member andmove the two sides toward one another until the jaw stop surfaces meet,when the sides of the slot will be parallel and able to retain theheaded pin therein.

Both these prior art documents disclose the use of pliers (or similar)to apply force on both sides of an orthodontic device and deform it.Such a method of deformation is unsuitable for the distalizing elementas herein described. The proper functioning of the distalizer is basedon the collaboration between the surfaces of the ball member and thereceptacle, which define collision points and upon which the distalizingeffect is dependent. A proper treatment of a malocclusion with adistalizer would not be possible if either the ball member of thereceptacle had an imperfection.

There thus exists a need to improve the method of manufacture and/orassembly of the distalizer that avoids or reduces these potentialproblems.

SUMMARY

According to a first aspect, a method of assembling a distalizer isprovided. The distalizer comprises a mesial element and a distalelement, and an arm connecting the distal element with the mesialelement, the arm having a ball member at one end of the arm and thedistal element having a receptacle for receiving said ball member. Themethod comprises providing the distal element with an opening of thereceptacle that is large enough to introduce the ball member withoutsubstantially having to deform either the ball member or the border ofthe receptacle. The method further comprises providing the arm with theball member, and introducing the ball member into the receptacle. Afterintroduction of the ball member into the receptacle, the opening of thereceptacle is reduced.

In this aspect, it can be accomplished that the ball member can berelatively easily inserted in the receptacle, and that it does notsuffer deformation during this insertion. By reducing the opening of thereceptacle after its introduction, damage to the ball member may beprevented and additionally it may be ensured that the ball member cannotexit the receptacle after insertion.

In certain implementations, reducing the opening of the receptacle maycomprise plastically deforming the border of the receptacle to reducethe opening of the receptacle. The distal element may thus bemanufactured in a single step, e.g. by moulding or micro injectionmoulding. After introduction of the ball member, the opening of thereceptacle may be reduced in a relatively simple deformation step andthe distalizer may be ready for use.

In some embodiments, the opening of the receptacle is at least partiallydelimited by a flange, and plastically deforming the receptaclecomprises pushing the flange inwards. Optionally, the flange may belocated substantially at a top portion of the opening of the receptacle.

In some embodiments, plastically deforming the receptacle compriseslocally deforming the border the receptacle. Local “pointwise”deformation may be enough to make sure the ball member cannot exit thereceptacle.

An example of plastically deforming the border of the receptaclecomprises coining.

In some embodiments, plastically deforming the border of the receptaclemay comprise heating up the border. In other embodiments, thedeformation of the border may take place at room temperature. Dependingon the deformation, and depending on the materials used, heating of thecomponents may be appropriate.

In some embodiments, the distalizer may be made from metal. In otherembodiments, the distalizer may be made from polymer. Furthermore, thedistalizer may be “hybrid”, i.e. the mesial element may be made frompolymers and the distal element may be made from metal.

Optionally, reducing the opening of the receptacle may comprise addingan additional border element to the border of the receptacle. By addingan additional border element, the opening of the receptacle may bereduced. No deformation of any element would be needed in this case.Such an additional border element may be added by e.g. chemicallybonding or welding or even gluing. The additional border element may beof the same material as the distal element. Alternatively, theadditional border element may be of a different material, for example aceramic material, as long as a secure bond can be established.

In a further aspect, the present disclosure provides a distalizerobtainable by methods substantially as hereinbefore described.

Additional objects, advantages and features of embodiments of theinvention will become apparent to those skilled in the art uponexamination of the description, or may be learned by practice of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

Particular embodiments of the present invention will be described in thefollowing by way of non-limiting examples, with reference to theappended drawings, in which:

FIG. 1 illustrates some of the terminology used herein;

FIGS. 2 a-2 c illustrate a distalizer according to some embodiments;

FIGS. 3 a-3 d illustrate various embodiments of the present invention;and

FIGS. 4 a and 4 b schematically illustrate further embodiments of thepresent invention.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1 schematically illustrates the arrangement of teeth in the lowerjaw (mandible). A front portion of the mouth 110 may be referred to as amesial region. A rear portion of the mouth 120 may be referred to as adistal region. An inner portion of the mouth behind the teeth 130 may bereferred to as a lingual region. An outer portion of the mouth 140 maybe referred to as a labial region. A mesial-distal direction 115 withrespect to a specific tooth (first molar) has been schematicallyindicated in FIG. 1. Also indicated in FIG. 1 is a lingual-labialdirection 135 with respect to the same tooth. This terminology will beadhered to in the present disclosure.

FIG. 2 a-2 c illustrate a distalizer adapted for the segmentaldistalization of the canine-to-molar posterior maxillary area. FIG. 2 aillustrates a mesial element 10 comprising a mesial base 11 with an arm13 integrally formed with the mesial element. The mesial elementcomprises a base surface 12 which is adapted to be fitted on a maxillarycanine. The base may comprise a surface that is particularly suited forretention on the tooth once attached using adhesives. In the illustratedembodiment, a number of dovetail protrusions are incorporated for thispurpose. However, other retention elements may be provided.

The hook 15 may be formed as a blunt forward (in the mesial direction)extension on the outer surface of the base 11. An elastic element, suchas e.g. a rubber band may be fitted around hook 15 for providing a“backwards” (mesial-distal direction) pulling force.

At the distal end of the arm 13, a ball element 14 is arranged. The ballelement is introduced in a receptacle 22 formed in the distal element20. The distal element 20 comprises a base surface 21 adapted to befitted on a maxillary molar, preferably the first molar. A border edge23 of the receptacle provides collision points to limit rotation of themolar around its palatal root. The inside of the receptacle definesfurther collision points to limit the backwards rotation of the molar.

FIG. 2 c illustrates a cross-section of the receptacle and the ballmember 14. Reference sign 25 indicates a border of the receptacle.

The distalizer may be made from any suitable material, such as e.g.metal (alloys) or polymers: the polymers may be fibre-reinforced or not.The different elements of the distalizer may also be made from differentmaterials. For example, the mesial element may be made from a polymer,and the distal element may be made from a metal (alloy).

The distal element and the mesial element may be manufactured in variousways. The elements may be moulded, both when they are made form metalsor polymers. When they are made from metals, they may also be made bymachining, e.g. by milling or cutting. The ball element may beintegrally formed with the arm or alternatively could be welded to thearm.

FIG. 3 a illustrates a first method of assembling in accordance withembodiments of the invention. The distal element comprises a receptaclewith an opening 25 that is large enough for introduction of the ballmember. Preferably, there is no elastic deformation of either the borderof the receptacle or the ball member during introduction. As such, anydamage to these elements may be minimized.

A flange 26, shown in interrupted line, which partially delimits theopening of the receptacle extends slightly outwards (i.e. in the labialdirection). Once the ball member has been introduced in the receptacle,the flange 26 may be plastically deformed, i.e. the flange may be pushedinwards in direction 30. As a result, the opening of the receptacle issmaller than before the introduction of the ball member, and it isimpossible for the ball member to slip out of the receptacle.

The plastic deformation may be carried out at room temperature,especially when the distalizer is made from metal. The deformation ofthe border of the receptacle may involve e.g. stamping, punching orcoining.

The plastic deformation may also be carried out after heating up of thedistalizer. This may be especially suitable when the distalizer elementsare made from polymers.

In the embodiment shown in FIG. 3 a, the flange extends substantiallyoutwards from the distal element before the deformation. After plasticdeformation, it is substantially flush with the rest of the border ofthe receptacle. In alternative embodiments, the flange may besubstantially flush with the remainder of the border before deformation,and extends substantially inwards after deformation.

FIG. 3 b illustrates in detail the resulting portion of the border ofthe receptacle.

Alternative embodiments are illustrated in FIG. 3 c. Instead ofdeforming a flange, or a substantial portion of the border of thereceptacle, the deformation after introduction of the ball member islocal. A mechanical deformation using very precise stamping may provokea local depression that is sufficient to keep the ball member in thereceptacle.

FIG. 3 d illustrates in detail the local deformation of the edge 25 ofthe opening. The depression 28 on the outer surface results in an inwardprotrusion 29 that delimits the receptacle and makes it impossible forthe ball member to come out of the receptacle.

FIGS. 4 a and 4 b schematically illustrate further embodiments. FIG. 4 aillustrates the ball member 14 at the end of arm 13 after beingintroduced into the receptacle of the distal element. The opening of thereceptacle is large enough for this introduction, without either theball member of the border of the receptacle being deformedsubstantially.

After this introduction, the additional border element 36 may beattached to edge 38 of the border of the receptacle. By adding borderelement 36, the resulting opening of the receptacle is reduced. The ballmember will thus be enclosed within the receptacle. FIG. 4 bschematically illustrates the result after adding the border element.The border element may be made from any suitable material as long as astrong attachment is established with the distal element.

The additional border element may e.g. be welded, or chemically bondedto the distal element. Alternatively, a mechanical connection betweenthe border of the receptacle and the additional border element, e.g.involving an interlocking of a male and female portion, may also beused. Such a mechanical connection may also be combined with e.g.bonding or adhesives.

Although only a number of particular embodiments and examples of theinvention have been disclosed herein, it will be understood by thoseskilled in the art that other alternative embodiments and/or uses of theinvention and obvious modifications and equivalents thereof arepossible. Furthermore, the present invention covers all possiblecombinations of the particular embodiments described. Thus, the scope ofthe present invention should not be limited by particular embodiments,but should be determined only by a fair reading of the claims thatfollow.

1. Method A method of assembling a distalizer, comprising: providing anarm connecting a distal element with a mesial element, the mesialelement adapted to be fixed by its base to an upper canine and thedistal element adapted to be fixed by its base to an upper molar,providing the arm with a ball member at one end thereof, providing areceptacle with a receptacle opening large enough to introduce the ballmember into the receptacle without substantial deformation of thereceptacle, introducing the ball member into the receptacle, andreducing the opening of the receptacle.
 2. The method according to claim1, wherein the reducing the opening of the receptacle comprisesplastically deforming a border of the receptacle to reduce the openingof the receptacle.
 3. The method according to claim 2, wherein theopening of the receptacle is at least partially delimited by a flangeand wherein the plastically deforming the receptacle comprises deformingthe flange by pushing the flange inwards.
 4. The method according toclaim 3, wherein the flange is located substantially at a top portion ofthe opening of the receptacle.
 5. The method according to claim 2,wherein the plastically deforming the receptacle comprises locallydeforming the border of the receptacle.
 6. The method according to claim5, wherein the plastically deforming the border of the receptaclecomprises at least one of the following: stamping, punching and coining.7. The method according to claim 2, wherein the plastically deformingthe border of the receptacle comprises heating the border.
 8. The methodaccording to claim 1, wherein the reducing the opening of the receptaclecomprises adding an additional border element to a pre-existing borderof the receptacle.
 9. The method according to claim 8, wherein theadding the additional border element comprises chemically bonding orwelding the additional border element to the receptacle.
 10. The methodaccording to claim 1, wherein the ball member shape is substantiallyspherical with two diametrically opposed planar surfaces, and thereceptacle of the distal element has a shape that is complementary tothe shape of the ball member.
 11. The method according to claim 1,wherein the ball member shape is substantially spherical, and thereceptacle of the distal element has a shape that is substantiallycomplementary to the shape of the ball member.
 12. The method accordingto claim 1, wherein the distalizer is made from a metal or a polymer orboth.
 13. The method according to claim 1, wherein the arm is integrallyformed with the mesial element.
 14. The method according to claim 1,wherein the distal element and/or the mesial element is moulded.
 15. Adistalizer obtainable by a method according to claim
 1. 16. A method ofassembling a distalizer, the method comprising: providing an armconnecting a distal element with a mesial element, the mesial elementadapted to be fixed by its base to an upper canine and the distalelement adapted to be fixed by its base to an upper molar, the armcomprising a ball member at one end of the arm and the distal elementcomprising a receptacle for receiving the ball member, wherein the ballmember is substantially spherical with two diametrically opposed planarsurfaces and the receptacle has a shape that is substantiallycomplementary to the shape of the ball member, providing the receptaclewith a receptacle opening large enough to introduce the ball member intothe receptacle without substantial deformation of the receptacle,introducing the ball member into the receptacle, and reducing theopening of the receptacle by locally plastically deforming the border ofthe receptacle by coining.
 17. The method according to claim 16, whereinthe distalizer is made from metal.
 18. The method according to claim 16,wherein the plastically deforming the border includes heating theborder.
 19. The method according to claim 16, wherein the arm isintegrally formed with the mesial element.